Substrate processing system

ABSTRACT

An apparatus for performing contaminant sensitive processing on a substrate. A substrate load chamber receives the substrate from an ambient contaminant laden environment, and isolates the substrate from the ambient contaminant laden environment. The substrate load chamber further forms a first environment of intermediate cleanliness around the substrate. A substrate pass through chamber receives the substrate from the substrate load chamber, and isolates the substrate from the intermediate cleanliness of the first environment of the substrate load chamber. The substrate pass through chamber further forms a second environment of high cleanliness around the substrate. A substrate transfer chamber receives the substrate from the substrate pass through chamber, and isolates the substrate from the high cleanliness of the second environment of the substrate pass through chamber. The substrate transfer chamber maintains a third environment of high cleanliness around the substrate, and transfers the substrate into more than one substrate processing chambers, where the substrate is selectively transferred into and out of the more than one substrate processing chambers without leaving the high cleanliness of the third environment. The substrate transfer chamber also selectively passes the substrate to the substrate pass through chamber when the substrate pass through chamber has formed the high cleanliness of the second environment. The substrate pass through chamber also receives the substrate from the substrate transfer chamber, and selectively passes the substrate to the substrate load chamber when the substrate load chamber has formed the intermediate cleanliness of the first environment. The substrate load chamber receives the substrate from the substrate pass through chamber, and selectively passes the substrate out of the substrate load chamber and into the ambient contaminant laden environment when the substrate load chamber is not open to the substrate pass through chamber.

FIELD

[0001] This invention relates to the field of integrated circuitfabrication. More particularly this invention relates to a system forperforming contaminant sensitive processing on a substrate.

BACKGROUND

[0002] A variety of different materials are typically used in integratedcircuit fabrication processes. Many of these materials are highlysusceptible to various contaminants. In addition, some processes, atintermediate points, create sites or structures that are verysusceptible to contamination. For example, when trenches or holes areetched into dielectric films, the dielectric films tend to be extremelysusceptible to contaminants in the atmosphere such as oxygen, nitrogen,rare gases, hydrocarbons, water vapor and other atmosphericcontaminants. When exposed to such, the etched portions of thedielectric layer tend to attract such contaminants.

[0003] In the specific case of low dielectric constant materials, whichtend to be porous in nature, the adsorption of contaminants tends to beeven greater. Thus, when a low dielectric constant material is etched,the etched portions tend to adsorb contaminants. Then, when a thinmaterial layer is subsequently deposited over the etched portions, suchas when a diffusion barrier is formed in a via, the contaminantsabsorbed in the low dielectric constant material in the area of theetched via tend to outgas and interfere with the uniform and desirabledeposition of the deposited layer. This condition tends to causeproblems with the integrated circuit, such as barrier layers that areporous or otherwise defection, and which do not exhibit the desiredbarrier properties.

[0004] As a more specific example, when a titanium adhesion layer isdeposited in an etched silicon oxide via, and then the titanium adhesionlayer is followed by a titanium nitride diffusion barrier layer, andthen the titanium nitride diffusion barrier layer is followed by atungsten plug deposition, the resultant structure often exhibits abreakdown of the barrier diffusion layer, which is typically referred toas poisoned vias or poisoned plugs.

[0005] What is needed, therefore, is a system for forming structures ona substrate, where the substrate and the various layers are not exposedto a contaminant laden environment.

SUMMARY

[0006] The above and other needs are met by an apparatus for performingcontaminant sensitive processing on a substrate. A substrate loadchamber receives the substrate from an ambient contaminant ladenenvironment, and isolates the substrate from the ambient contaminantladen environment. The substrate load chamber further forms a firstenvironment of intermediate cleanliness around the substrate.

[0007] A substrate pass through chamber receives the substrate from thesubstrate load chamber, and isolates the substrate from the intermediatecleanliness of the first environment of the substrate load chamber. Thesubstrate pass through chamber further forms a second environment ofhigh cleanliness around the substrate.

[0008] A substrate transfer chamber receives the substrate from thesubstrate pass through chamber, and isolates the substrate from the highcleanliness of the second environment of the substrate pass throughchamber. The substrate transfer chamber maintains a third environment ofhigh cleanliness around the substrate, and transfers the substrate intomore than one substrate processing chambers, where the substrate isselectively transferred into and out of the more than one substrateprocessing chambers without leaving the high cleanliness of the thirdenvironment.

[0009] The substrate transfer chamber also selectively passes thesubstrate to the substrate pass through chamber when the substrate passthrough chamber has formed the high cleanliness of the secondenvironment. The substrate pass through chamber also receives thesubstrate from the substrate transfer chamber, and selectively passesthe substrate to the substrate load chamber when the substrate loadchamber has formed the intermediate cleanliness of the firstenvironment. The substrate load chamber receives the substrate from thesubstrate pass through chamber, and selectively passes the substrate outof the substrate load chamber and into the ambient contaminant ladenenvironment when the substrate load chamber is not open to the substratepass through chamber.

[0010] Because there is a substrate pass through chamber between thesubstrate load chamber and the substrate transfer chamber, the highcleanliness environment of the substrate transfer chamber is neverexposed to the intermediate cleanliness of the substrate load chamber,or the contaminant laden ambient environment. Thus, the substrate passthrough chamber, by forming an environment of high cleanliness beforetransferring a substrate to or accepting a substrate from the substratetransfer chamber, protects and helps maintain the high cleanliness ofthe environment of the substrate transfer chamber. Therefore, thosecontaminant sensitive processes that are performed in the varioussubstrate processing chambers are not exposed to the environment ofintermediate cleanliness or to the contaminant laden ambientenvironment, and the intermediate structures which may be created bythese various processes are likewise not exposed to the environments oflesser cleanliness.

[0011] In another aspect of the invention, a method of performingcontaminant sensitive processing on a substrate is given. The substrateis transferred from an ambient contaminant laden environment and into asubstrate load chamber. The substrate is isolated from the ambientcontaminant laden environment with the substrate load chamber, and thesubstrate load chamber forms a first environment of intermediatecleanliness around the substrate.

[0012] The substrate is transferred from the intermediate cleanliness ofthe first environment of the substrate load chamber and into a substratepass through chamber, where the substrate is isolated from theintermediate cleanliness of the first environment of the substrate loadchamber. A second environment of high cleanliness is formed around thesubstrate with the substrate pass through chamber.

[0013] The substrate is transferred from the high cleanliness of thesecond environment of the substrate pass through chamber and into asubstrate transfer chamber, where a third environment of highcleanliness is maintained around the substrate. The substrate isselectively transferred into more than one substrate processingchambers, where the substrate is selectively transferred into and out ofthe more than one substrate processing chambers without leaving the highcleanliness of the third environment. The substrate is selectivelyprocessed in the more than one substrate processing chambers.

[0014] The substrate is transferred to the substrate pass throughchamber from the substrate transfer chamber when the substrate passthrough chamber has formed the high cleanliness of the secondenvironment and the substrate pass through chamber is not open to thesubstrate load chamber. The substrate is transferred to the substrateload chamber from the substrate pass through chamber when the substrateload chamber has formed the intermediate cleanliness of the firstenvironment and the substrate pass through chamber is not open to thesubstrate transfer chamber. The substrate is transferred out of thesubstrate load chamber and into the ambient contaminant ladenenvironment when the substrate load chamber is not open to the substratepass through chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Further advantages of the invention are apparent by reference tothe detailed description when considered in conjunction with thefigures, which are not to scale so as to more clearly show the details,wherein like reference numbers indicate like elements throughout theseveral views, and wherein:

[0016]FIG. 1 is a functional block diagram of an apparatus according tothe present invention,

[0017]FIG. 2 is cross sectional diagram of a substrate, including alayer,

[0018]FIG. 3 is a cross sectional diagram of a via etched in the layerof the substrate,

[0019]FIG. 4 is a cross sectional diagram of an adhesion layer depositedin the via of the substrate,

[0020]FIG. 5 is a cross sectional diagram of a barrier layer depositedin the via of the substrate, and

[0021]FIG. 6 is a cross sectional diagram of a plug layer deposited inthe via of the substrate.

DETAILED DESCRIPTION

[0022] Referring now to FIG. 1, there is depicted an apparatus 10according to the present invention. Substrates are transferred into andout of the apparatus 10 via a substrate load chamber 12, which can beselectively isolated from the contaminant laden ambient environmentaround the apparatus 10 via a load lock mechanism 32. By contaminantladen environment, it is not necessarily meant that the ambientenvironment is filthy. Rather, it is intended to mean that the ambientenvironment contains some sort of material that is detrimental to amaterial, process, or structure that is to be deposited, used, orexposed at a point in time during the desired processing of thesubstrate. Thus, even oxygen or water, such as water vapor, may beconsidered a contaminant within the present context. It is anticipatedthat the load lock 32 of the substrate load chamber 12 will open up intoa clean room facility.

[0023] Once the substrate is brought within the substrate load chamber12, the load lock 32 is closed, isolating the substrate from thecontaminant laden ambient environment. An environment of intermediatecleanliness is preferably formed around the substrate once it is withinthe substrate load chamber 12. This is preferably accomplished bydrawing a vacuum within the substrate load chamber 12, such as by usinga first pumping system 26 that is in communication with the substrateload chamber 12 via a vacuum line 40. In the most preferred embodiment,the first pumping system 26 is a roughing pump, such as a rotary vanepump, which reduces the pressure within the substrate load chamber 12 toat least about 10⁻³ torr.

[0024] By reducing the pressure within the substrate load chamber 12 inthis manner, a first environment of intermediate cleanliness if formed.The first environment has an intermediate cleanliness because much ofthe matter of the contaminant laden ambient environment has been removedby drawing a vacuum on the first environment. Thus, much of what isdetrimental to the later processes, materials, and structures has beenremoved from the first environment. Further, the first environment isnot as clean as is ultimately desired, and thus the first environment isdesignated as having an intermediate cleanliness that is somewherebetween the contaminant laden ambient environment and the cleanerenvironment that is ultimately desired.

[0025] The substrate is brought into a substrate pass through chamber14, such as by opening a load lock 34 between the substrate load chamber12 and the substrate pass through chamber 14. In the preferredembodiment, the load lock 34 between the substrate pass through chamber14 and the substrate load chamber 12 is not opened unless the load lock32 is closed and the first environment of intermediate cleanliness hasbeen formed in the substrate load chamber 12. In this manner, thesubstrate pass through chamber 14 is kept isolated from the contaminantladen ambient environment.

[0026] Once the substrate is brought within the substrate pass throughchamber 14, the load lock 34 is closed, isolating the substrate from theintermediate cleanliness of the first environment of the substrate loadchamber 12. A second environment of high cleanliness is preferablyformed around the substrate once it is within the substrate pass throughchamber 14. This is preferably accomplished by drawing a vacuum withinthe substrate pass through chamber 14, such as by using a second pumpingsystem 28 that is in communication with the substrate pass throughchamber 14 via a vacuum line 42. In the most preferred embodiment, thesecond pumping system 28 is a cryogenic pump, or some other high vacuumtype pump such as a diffusion pump or molecular pump, which reduces thepressure within the substrate pass through chamber 14 to at least about10⁻⁷ torr. In another embodiment, the first pumping system 26 and thesecond pumping system 28 are the same pumping system that isappropriately valved to the substrate pass through chamber 14 and thesubstrate load chamber 12.

[0027] By reducing the pressure within the substrate pass throughchamber 14 in this manner, a second environment of high cleanliness ifformed. The second environment has a high cleanliness because anadditional amount of the matter of the intermediate cleanlinessenvironment has been removed by drawing a higher vacuum on the secondenvironment. Thus, even more of what is detrimental to the laterprocesses has been removed from the second environment. The secondenvironment may still not be as clean as is ultimately desired, for avariety of reasons. For example, because the substrate pass throughchamber 14 is intermittently exposed to the intermediate cleanliness ofthe first environment, it may not be able to become as clean as anenvironment that is not intermittently exposed to the intermediatecleanliness of the first environment, but which is rather more isolatedfrom sources of contaminants.

[0028] The substrate is brought into a substrate transfer chamber 16,such as by opening a load lock 36 between the substrate pass throughchamber 14 and the substrate transfer chamber 16. In the preferredembodiment, the load lock 36 between the substrate pass through chamber14 and the substrate transfer chamber 16 is not opened unless the loadlock 34 between the substrate pass through chamber 14 and the substrateload chamber 12 is closed and the second environment of high cleanlinesshas been formed in the substrate pass through chamber 14. In thismanner, the substrate transfer chamber 16 is kept isolated from theintermediate cleanliness of the first environment in the substrate loadchamber 12.

[0029] Once the substrate is brought within the substrate transferchamber 16, the load lock 36 is closed, isolating the substrate from thehigh cleanliness environment of the substrate pass through chamber 14.An environment of high cleanliness is preferably maintained around thesubstrate once it is within the substrate transfer chamber 16. This ispreferably accomplished by drawing a vacuum within the substratetransfer chamber 16, such as by using a third pumping system 30 that isin communication with the substrate transfer chamber 16 via a vacuumline 44. In the most preferred embodiment, the third pumping system 30is a cryogenic pump, or some other high vacuum type pump such as adiffusion pump or molecular pump, which reduces the pressure within thesubstrate transfer chamber 16 to about 10⁻⁸ torr. Thus, the environmentof high cleanliness within the substrate transfer chamber 16 ispreferably even cleaner than that formed within the substrate passthrough chamber 14.

[0030] In one embodiment, the first pumping system 26, the secondpumping system 28, and the third pumping system 30 are all the samepumping system, which is appropriately valved to the substrate transferchamber 16, the substrate pass through chamber 14, and the substrateload chamber 12.

[0031] With the substrate inside of the substrate transfer chamber 16,the substrate may now be selectively transferred into and out of variousprocessing chambers, such as first processing chamber 18, secondprocessing chamber 20, third processing chamber 22, and fourthprocessing chamber 24. It is appreciated that the number of processingchambers may be either greater than or less than the number depicted inFIG. 1 and described in this embodiment. Most preferably, the processingchambers are each selectively isolated from the substrate transferchamber 16, such as by load locks 38.

[0032] With the processing chambers isolated from the contaminant ladenambient environment and the first environment of intermediatecleanliness, the processes conducted within the processing chambers, thematerial used within the processing chambers, and the intermediatestructures formed within the processing chambers are all isolated fromthe contaminants within those relatively contaminated environments.Thus, processes, materials, and structures which are sensitive to thecontaminants within the ambient environment or the intermediatecleanliness of the first environment may be more safely processed withinthe processing chambers.

[0033] For example, FIG. 2 depicts a substrate having a bottom layer 102and a top layer 100. In FIG. 3, a via 104 has been etched within the toplayer 100, which via 104 extends down to the bottom layer 102. In aspecific example where the top layer 100 is a porous dielectric layer,such as a low dielectric constant layer, the freshly etched sidewalls ofthe via 104 tend to be extremely hydroscopic and readily adsorb waterfrom an ambient environment. Thus, it is most preferred to etch vias 104within one of the processing chambers of the apparatus 10, such aswithin the first processing chamber 18, so that the resultant structure,the etched via 104, is not exposed to undue levels of the water vaporcontamination.

[0034] After the via 104 is etched, the substrate is preferablytransferred to another chamber for further processing, such as to thesecond processing chamber 20. In the second processing chamber 20, alayer of a material may be deposited over the clean surfaces of the via104. For example, as depicted in FIG. 4, a thin layer of an adhesionmaterial 106, such as titanium, may be deposited in the via 104. Afterthe adhesion layer 106 is deposited, the substrate may be removed fromthe apparatus 10 as described below. However, in a most preferredembodiment, the cleanliness of the environment within the substratetransfer chamber 16 is more fully utilized by processing the substratefurther.

[0035] For example, as depicted in FIG. 5, an additional layer, such asa barrier layer 108 may be deposited over the adhesion layer 106. Thebarrier layer 108 may be of a material such as titanium nitride, that isdeposited in the third processing chamber 22. After the barrier layer108 is deposited, the substrate may be removed from the apparatus 10 asdescribed below. However, in a most preferred embodiment, thecleanliness of the environment within the substrate transfer chamber 16is more fully utilized by processing the substrate further.

[0036] For example, as depicted in FIG. 6, and additional layer, such asa plug layer 110 maybe deposited over the barrier layer 108. The pluglayer 110 may be of a material such as tantalum, that is deposited inthe fourth processing chamber 24. After the plug layer 110 is deposited,the substrate is preferably removed from the apparatus 10.

[0037] In other embodiments, the via 104 is etched in the firstprocessing chamber 18, and the etched via 104 is then cleaned in thesecond processing chamber 20. An adhesion layer 106 of titanium is thendeposited by sputter deposition in the third processing chamber 22, anda barrier layer 108 of titanium nitride is deposited by chemical vapordeposition in the fourth processing chamber 24. Alternately, after theclean in the second processing chamber 20 is performed, a barrier layerof tantalum is sputter deposited in the third processing chamber 22, anda layer 110 of copper is sputter deposited in the fourth processingchamber 24.

[0038] It is appreciated that the number of process steps performedwithin the apparatus 10, the materials described in the specificexamples above, and the types of process steps so described are all byway of example only. In various embodiments, different numbers and typesof process steps may be performed within the apparatus 10.

[0039] The substrate is withdrawn from the apparatus 10 by transferringit from the substrate transfer chamber 16 when the second environment ofhigh cleanliness has been formed in the substrate pass through chamber14, and the load lock 34 between the substrate pass through chamber 14and the substrate load chamber 12 is closed. The load lock 36 betweenthe substrate transfer chamber 16 is then closed, and the load lock 34is opened when the first environment of intermediate cleanliness hasbeen formed within the substrate load chamber 12 and the load lock 32 isclosed. The substrate is then transferred into the substrate loadchamber 12, and the load lock 34 between the substrate pass throughchamber 14 and the substrate load chamber 12 is closed. Finally, theload lock 32 is opened when the load lock 34 is closed, and thesubstrate is withdrawn from the apparatus 10 into the contaminant ladenambient environment.

[0040] Thus, by using the apparatus 10 according to the method asdescribed above, all of the processes, materials, and structures thatare preferably isolated from the contaminant laden ambient environmentare so isolated, and the substrate is only exposed to the contaminantladen ambient environment at such points in the processing when suchexposure is not unduly detrimental to the exposed materials andstructures on the substrate.

[0041] The foregoing description of preferred embodiments for thisinvention have been presented for purposes of illustration anddescription. They are not intended to be exhaustive or to limit theinvention to the precise form disclosed. Obvious modifications orvariations are possible in light of the above teachings. The embodimentsare chosen and described in an effort to provide the best illustrationsof the principles of the invention and its practical application, and tothereby enable one of ordinary skill in the art to utilize the inventionin various embodiments and with various modifications as is suited tothe particular use contemplated. All such modifications and variationsare within the scope of the invention as determined by the appendedclaims when interpreted in accordance with the breadth to which they arefairly, legally, and equitably entitled.

What is claimed is:
 1. An apparatus for performing contaminant sensitive processing on a substrate, comprising: a substrate load chamber for receiving the substrate from an ambient contaminant laden environment, for isolating the substrate from the ambient contaminant laden environment, and for forming a first environment of intermediate cleanliness around the substrate, a substrate pass through chamber for receiving the substrate from the substrate load chamber, for isolating the substrate from the intermediate cleanliness of the first environment of the substrate load chamber, and for forming a second environment of high cleanliness around the substrate, a substrate transfer chamber for receiving the substrate from the substrate pass through chamber, for isolating the substrate from the high cleanliness of the second environment of the substrate pass through chamber, for maintaining a third environment of high cleanliness around the substrate, and for transferring the substrate into more than one substrate processing chambers, where the substrate is selectively transferred into and out of the more than one substrate processing chambers without leaving the high cleanliness of the third environment, the substrate transfer chamber also for selectively passing the substrate to the substrate pass through chamber when the substrate pass through chamber has formed the high cleanliness of the second environment, the substrate pass through chamber also for receiving the substrate from the substrate transfer chamber, and for selectively passing the substrate to the substrate load chamber when the substrate load chamber has formed the intermediate cleanliness of the first environment, and the substrate load chamber for receiving the substrate from the substrate pass through chamber, and for selectively passing the substrate out of the substrate load chamber into the ambient contaminant laden environment when the substrate load chamber is not open to the substrate pass through chamber.
 2. The apparatus of claim 1 wherein the more than one substrate processing chambers include an etch chamber and a deposition chamber.
 3. The apparatus of claim 1 wherein the more than one substrate processing chambers include an etch chamber, a titanium deposition chamber, a titanium nitride deposition chamber, and a tantalum deposition chamber.
 4. The apparatus of claim 1 wherein the more than one substrate processing chambers include an etch chamber, a clean chamber, a tantalum deposition chamber, and a copper deposition chamber.
 5. The apparatus of claim 1 further comprising a first load lock for selectively isolating the substrate load chamber from the substrate pass through chamber.
 6. The apparatus of claim 1 further comprising a second load lock for selectively isolating the substrate pass through chamber from the substrate transfer chamber.
 7. The apparatus of claim 1 further comprising at least one third load lock for selectively isolating the substrate transfer chamber from the more than one substrate processing chambers.
 8. The apparatus of claim 1 further comprising: a first pumping system for selectively forming the first environment of intermediate cleanliness in the substrate load chamber, a second pumping system for selectively forming the second environment of high cleanliness in the substrate pass through chamber, and a third pumping system for selectively forming the third environment of high cleanliness in the substrate transfer chamber.
 9. The apparatus of claim 1 further comprising a first roughing pump for selectively forming the first environment of intermediate cleanliness in the substrate load chamber,
 10. The apparatus of claim 1 further comprising a first cryogenic pump for selectively forming the second environment of high cleanliness in the substrate pass through chamber,
 11. The apparatus of claim 1 further comprising a second cryogenic pump for selectively forming the third environment of high cleanliness in the substrate transfer chamber,
 12. A method of performing contaminant sensitive processing on a substrate, comprising the steps of: transferring the substrate from an ambient contaminant laden environment and into a substrate load chamber, isolating the substrate from the ambient contaminant laden environment with the substrate load chamber, forming a first environment of intermediate cleanliness around the substrate in the substrate load chamber, transferring the substrate from the intermediate cleanliness of the first environment of the substrate load chamber and into a substrate pass through chamber, isolating the substrate from the intermediate cleanliness of the first environment of the substrate load chamber with the substrate pass through chamber, forming a second environment of high cleanliness around the substrate with the substrate pass through chamber, transferring the substrate from the high cleanliness of the second environment of the substrate pass through chamber and into a substrate transfer chamber, isolating the substrate from the high cleanliness of the second environment of the substrate pass through chamber with the substrate transfer chamber, maintaining a third environment of high cleanliness around the substrate with the substrate transfer chamber, selectively transferring the substrate into more than one substrate processing chambers, where the substrate is selectively transferred into and out of the more than one substrate processing chambers without leaving the high cleanliness of the third environment, selectively processing the substrate in the more than one substrate processing chambers, transferring the substrate to the substrate pass through chamber from the substrate transfer chamber when the substrate pass through chamber has formed the high cleanliness of the second environment and the substrate pass through chamber is not open to the substrate load chamber, transferring the substrate to the substrate load chamber from the substrate pass through chamber when the substrate load chamber has formed the intermediate cleanliness of the first environment and the substrate pass through chamber is not open to the substrate transfer chamber, and transferring the substrate out of the substrate load chamber and into the ambient contaminant laden environment when the substrate load chamber is not open to the substrate pass through chamber.
 13. The method of claim 12 wherein the step of processing the substrate in the more than one substrate processing chambers further comprises: etching the substrate in an etch chamber, cleaning the substrate in a clean chamber, and depositing a layer in a deposition chamber.
 14. The method of claim 12 wherein the step of processing the substrate in the more than one substrate processing chambers further comprises: etching the substrate in an etch chamber, cleaning the substrate in a clean chamber, and depositing a layer of titanium in a deposition chamber.
 15. The method of claim 12 wherein the step of processing the substrate in the more than one processing chambers further comprises: etching the substrate in an etch chamber, cleaning the substrate in a clean chamber, depositing a layer of tantalum in a first deposition chamber, and depositing a layer of copper in a second deposition chamber.
 16. The method of claim 12 further comprising the step of selectively isolating the substrate load chamber from the substrate pass through chamber with a first load lock.
 17. The method of claim 12 further comprising the step of selectively isolating the substrate pass through chamber from the substrate transfer chamber with a second load lock.
 18. The method of claim 12 further comprising the step of selectively isolating the substrate transfer chamber from the more than one substrate processing chambers with at least one third load lock.
 19. The method of claim 12 wherein: the step of forming the first environment of intermediate cleanliness in the substrate load chamber further comprises using a first pumping system, the step of forming the second environment of high cleanliness in the substrate pass through chamber further comprises using a second pumping system, and the step of forming the third environment of high cleanliness in the substrate transfer chamber further comprises using a third pumping system.
 20. A method of forming a via on a substrate of a low dielectric constant material, comprising the steps of: forming a first environment of intermediate cleanliness around the substrate with a substrate load chamber that receives the substrate from an ambient contaminant laden environment and isolates the substrate from the ambient contaminant laden environment, forming a second environment of high cleanliness around the substrate with a substrate pass through chamber that receives the substrate from the substrate load chamber and isolates the substrate from the intermediate cleanliness of the first environment of the substrate load chamber, maintaining a third environment of high cleanliness around the substrate with a substrate transfer chamber that receives the substrate from the substrate pass through chamber and isolates the substrate from the high cleanliness of the second environment of the substrate pass through chamber, transferring the substrate into more than one substrate processing chambers, where the substrate is selectively transferred into and out of the more than one substrate processing chambers without leaving the high cleanliness of the third environment, etching the substrate in an etch chamber to form a via recess, depositing a titanium adhesion layer in a first deposition chamber, depositing a titanium nitride diffusion barrier layer in a second deposition chamber, selectively transferring the substrate to the substrate pass through chamber from the substrate transfer chamber when the substrate pass through chamber has formed the high cleanliness of the second environment, selectively transferring the substrate to the substrate load chamber from the substrate pass through chamber at a time when the substrate load chamber has formed the intermediate cleanliness of the first environment, and selectively transferring the substrate out of the substrate load chamber into the ambient contaminant laden environment at a time when the substrate load chamber is not open to the substrate pass through chamber. 